1. Anyone who has ever actively and knowingly participated in an act of terrorism, anywhere in the world, that resulted in the death(s) of innocent people would have all of the physical and emotional pain they caused returned to them, and they would remain alive only long enough to experience every last bit of it.
2. I'd recalibrate the balance of nature so that spiders were no longer a part of it, and they'd all disappear.
3. I'd bring back Arrested Development, Futurama, Firefly, Freaks and Geeks, Wonderfalls, and Farscape, make them all top ten hits with commitments from their various networks to remain on the air until they're ready to end on their own. (in case you're wondering, the other shows in the top 10 would be Scrubs, The Office, Veronica Mars, and Monk)
4. Steelers win the Super Bowl
If I ran out of ideas after that, I'd contact DuelLadyS, because most of her ideas seemed just about perfect to me.